Determination of safe back-driving currents in bond wires and dice

The most obvious damage mechanism in backdriven bond wires during circuit-board testing is overheating which can, in extreme cases, cause melting of the wire. The authors outline experiments to assess the effects of temperature, current density and number of pulses in aluminium wires so that realistic limits may be set for backdriving. Another potential damage mechanism is overheating of the semiconductor junctions within the die, leading to second breakdown and subsequent thermal runaway. Simple algorithms have been developed to predict the junction temperature for a given device in terms of the power dissipation pulse duration and the geometry of the backdriven transistor